For the most part, Oprah's life has been an open book. "I think I've seen just about everything and heard every story," she says. "I thought nothing could surprise me anymore. But let me tell you, I was wrong."

Just before Thanksgiving 2010, Oprah received some news about her family that she says shook her to her core. "[It's] a bombshell family secret that left me speechless," she says. "Only a handful of people in my life know about this."

With the way the media works today, Oprah says there's no way the story wouldn't eventually get out, so she and her family made the decision to do this show. "I wanted you to hear it from me first," she says. It all starts with one woman's story...a mother from Milwaukee who discovered she's Oprah's half-sister.